Facebook App Not Working

The Last.fm Facebook app is broken...
The discussion on the facebook board for the app: http://www.facebook.com/topic.php?uid=2381079642&topic=4921&ref=mf
A repost of what I said there:

Same issue, but it appears to be with malformed post data or some other problem upon submit to:
http://www.last.fm/login/appAuth?lang=en
This subsequently causes that page to kick out to:
http://www.last.fm/?invalid_session=1
Eventually just sending me to:
http://www.last.fm/home
When I'm logged in and all...seems to be a problem authenticating the app to my Last.fm account.